Copy clang headers to reduce dependencies

This commit copies clang headers to reduce dependencies between
repositories.  Binaries under `prebuilts/clang-tools` should always uses
the clang headers distributed with themselves.

Bug: 111579848
Test: `clang-headers` is in `build-prebuilts.zip`.
Change-Id: Iaa233fe3ff628a23878163bef2dee19af978c464
1 file changed
tree: 48f66bf189b60f780bb583ad08c027a254afb2e2
  1. darwin-x86/
  2. linux-x86/
  3. build-prebuilts.sh
  4. manifest.xml